U.S. patent number 6,559,461 [Application Number 09/689,823] was granted by the patent office on 2003-05-06 for wafer scanning support unit of ion implantation apparatus.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Sang-Il Seo.
United States Patent |
6,559,461 |
Seo |
May 6, 2003 |
Wafer scanning support unit of ion implantation apparatus
Abstract
A wafer scanning support unit of an ion implantation apparatus
includes a vacuum chamber having an opening in one side thereof for
admitting an ion beam, and a wafer scanning support disposed within
the vacuum chamber for supporting a wafer at an inclination and
moving the wafer up and down in front of the ion beam so that the
wafer is scanned. The wafer scanning support includes a scan shaft
pivotally mounted about a horizontal axis so that it can be
inclined relative to the vertical, an elevating member slidingly
coupled to the scan shaft so as to be movable therealong, a driving
motor for moving the elevating member up and down along the scan
shaft, and a wafer holder connected to the elevating member so as
to be movable therewith. The inclined wafer holder is moved along
an inclined path corresponding to the inclination of the scan
shaft, so that the ion beam travels substantially the same distance
to impinge all portions of the wafer including the uppermost and
bottommost parts. Thus, the ion-implantation process is carried out
uniformly across the surface of the wafer. In addition, the
position of the scan shaft can be set based on the parameters of
the process, such as the size of the wafer and the desired
characteristics produced by the ion-implantation process.
Inventors: |
Seo; Sang-Il (Inchon,
KR) |
Assignee: |
Samsung Electronics Co., Ltd.
(Suwon, KR)
|
Family
ID: |
19621149 |
Appl.
No.: |
09/689,823 |
Filed: |
October 13, 2000 |
Foreign Application Priority Data
|
|
|
|
|
Nov 22, 1999 [KR] |
|
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99-51880 |
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Current U.S.
Class: |
250/492.21;
250/398; 250/442.11 |
Current CPC
Class: |
H01L
21/68 (20130101); H01J 37/3171 (20130101); H01J
2237/202 (20130101); H01J 2237/20228 (20130101) |
Current International
Class: |
H01L
21/67 (20060101); H01L 21/68 (20060101); H01J
37/317 (20060101); H01J 037/30 () |
Field of
Search: |
;250/492.21,442.11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lee; John R.
Assistant Examiner: Gurzo; Paul
Attorney, Agent or Firm: Volentine Francos, PLLC
Claims
What is claimed is:
1. A wafer scanning support unit of an ion implantation apparatus,
comprising: a vacuum chamber having an opening at one side thereof
for admitting an ion beam into the chamber; and a scanning wafer
support disposed within said vacuum chamber, said wafer scanning
support including a fixing member, a vertically extending scan
shaft mounted to said fixing member so as to be pivotable in a
plane about a first horizontal axis, whereby the inclination of the
scan shaft, relative to the vertical, can be changed, an elevating
member slidingly fitted to said scan shaft so as to be movable up
and down therealong, a first driving motor engaged with said
elevating member so as to drive said elevating member along said
scan shaft, a horizontal transfer member coupled to said elevating
member so as to move vertically therewith and so as to be movable
horizontally relative thereto within said plane, a horizontal
driving motor engaged with said horizontal transfer member so as to
move said horizontal transfer member horizontally along said plane
relative to said scan shaft and elevating member, a vertical
transfer member coupled to said horizontal transfer member so as to
move horizontally therewith, a vertical driving motor engaged with
said vertical transfer member so as to move said vertical transfer
member vertically, and a wafer holder mounted to said vertical
transfer member for vertical and horizontal translational movement
with said vertical transfer member and said horizontal transfer
member, respectively, independently of the pivotal movement of said
scan shaft.
2. The wafer scanning support unit support unit as claimed in claim
1, and further comprising a horizontally extending hinge pin
extending into said fixing member and into an end of said scan
shaft, said hinge pin pivotally mounting said scan shaft to said
fixing member, gear teeth integral with said end of the scan shaft,
a gear intermeshed with said gear teeth, and a second driving motor
having an output shaft to which said gear is connected, whereby
said second driving motor operates to place said scan shaft in
position at an inclination relative to the vertical.
3. The wafer scanning support unit support unit as claimed in claim
1, and further comprising a cylinder mounted to said elevating
member, said horizontal transfer member being slidingly coupled to
said cylinder, and wherein said horizontal driving motor is mounted
to said cylinder and has a threaded output shaft in a threaded
mating engagement with said horizontal transfer member, whereby
rotation of said threaded output shaft by said horizontal driving
motor moves said horizontal transfer member vertically relative to
said cylinder.
4. The wafer scanning support unit support unit as claimed in claim
1, and further comprising a cylinder fixed to an end of said
horizontal transfer member so as to move therewith, said vertical
transfer member being slidingly coupled to said cylinder so as to
be movable vertically relative thereto, and wherein said vertical
driving motor is mounted to said cylinder and has a threaded output
shaft in a threaded mating engagement with said vertical transfer
member, whereby rotation of said threaded output shaft by said
vertical driving motor moves said vertical transfer member
vertically relative to said cylinder.
5. The wafer scanning support unit support unit as claimed in claim
1, and further comprising a rotary coupling pivotally connecting
said vertical transfer member to said horizontal transfer member
about a second horizontal axis parallel to said first horizontal
axis, whereby the inclination of said vertical transfer member
relative to the scan shaft can be adjusted.
6. The wafer scanning support unit support unit as claimed in claim
5, wherein said coupling comprises a protrusion connected to said
vertical transfer member, and a protrusion driving motor supported
by said horizontal transfer member and having a rotary output shaft
extending through an end of the horizontal transfer member and
fixed to said protrusion.
7. The wafer scanning support unit support unit as claimed in claim
1, and further comprising a supporting member fixed to said
vertical transfer member, and a rotary member to which said wafer
holder is mounted, said rotary member being rotatably supported by
said supporting member and slidingly engaged therewith about a
plane inclined by about 45.degree. relative to the vertical,
whereby rotation of said rotary member relative to said supporting
member can move said wafer holder between respective positions at
which the wafer holder faces said opening in the vacuum chamber and
faces upwardly to facilitate the loading and unloading of a
wafer.
8. A wafer scanning support of an ion implantation apparatus,
comprising: a fixing member; a vertically extending scan shaft
mounted to said fixing so as to be pivotable in a plane about a
first horizontal axis, whereby the inclination of the scan shaft,
relative to the vertical, can be changed; an elevating member
slidingly coupled to said scan shaft so as to be movable
therealong; a driving motor engaged with said elevating member for
moving the elevating member up and down along the scan shaft; a
wafer holder connected to the elevating member so as to move
therewith; and a horizontal transfer member movable horizontally
along said plane independently of the pivotal movement of said scan
shaft in said plane, said wafer holder being coupled to said
horizontal transfer member for horizontal translational movement
such that the wafer holder is also movable horizontally along said
plane independently of the pivotal movement of said scan shaft in
said plane.
9. The wafer scanning support as claimed in claim 8, wherein said
horizontal transfer member is coupled with and extends from said
elevating member, and further comprising a vertical member
supporting said wafer holder, and a rotary coupling interconnecting
said horizontal transfer and vertical members such that the
vertical member is rotatable relative to said horizontal transfer
member about a second horizontal axis parallel to said first
horizontal axis.
10. The wafer scanning support as claimed in claim 8, and further
comprising a first cylinder fixed to said elevating member, said
horizontal transfer member being fitted to said first cylinder so
as to be slidable relative thereto in a horizontal linear direction
in said plane, a second cylinder coupled to said horizontal
transfer member, and a vertical transfer member fitted to said
second cylinder so as to be slidable relative thereto in a vertical
direction, said wafer holder being mounted to said vertical
transfer member.
11. The wafer scanning support as claimed in claim 10, and further
comprising a rotary coupling interconnecting said horizontal
transfer member and said second cylinder such that said vertical
transfer member is rotatable relative to said horizontal transfer
member about a second horizontal axis parallel to said first
horizontal axis.
12. The wafer scanning support as claimed in claim 11, wherein said
rotary coupling comprises a drive motor for rotating said second
cylinder about said second horizontal axis relative to said
horizontal transfer member.
13. The wafer scanning support as claimed in claim 10, and further
comprising a horizontal driving motor supported by said first
cylinder and engaged with said horizontal transfer member so as to
move said horizontal transfer member horizontally, and a vertical
driving motor supported by said second cylinder and engaged with
said vertical transfer member so as to move said vertical transfer
member vertically.
14. The wafer scanning support as claimed in claim 10, and further
comprising a horizontally extending hinge pin extending into said
fixing member and into an end of said scan shaft, said hinge pin
pivotally mounting said scan shaft to said fixing member, gear
teeth integral with said end of the scan shaft, a gear intermeshed
with said gear teeth, and a driving motor having an output shaft to
which said gear is connected, whereby said driving motor operates
to place said scan shaft in position at an inclination relative to
the vertical.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ion implantation apparatus.
More particularly, the present invention relates to an ion
implantation apparatus for scanning a wafer with an ion beam to
implant ions into the surface of the wafer in the fabricating of a
semiconductor device.
2. Description of the Related Art
In general, an ion implantation process is one of the processes
used to fabricate a semiconductor device. In this process,
particles of a predetermined impurity are accelerated and are
formed into an ion beam directed towards a particular part of a
wafer. The ion beam or the wafer is continually moved horizontally
or vertically, whereby the ions are implanted into the entire
surface of the wafer.
A conventional ion implantation apparatus is disclosed in Japanese
Patent No. Hei 04-283923. The apparatus, as shown in FIG. 1,
comprises: parallel ion beam radiating means 10, a mask 16 having a
slit 17 therein, a support plate 12 for supporting a wafer 11,
elevation driving means 14 for raising and lowering the support
plate 12 via a driving shaft 13 integral with a bottom part of the
support plate 12, and an electrostatic flux type of charge monitor
15 disposed near the bottom of the ion beam A as it passes through
the slit 17 in the mask 16.
The parallel ion beam radiating means 10 produces an ion beam A.
The ion beam A passes through the slit 17 of the mask 16, and is
accelerated by a separate speed-up pipe. Then the ions of the beam
A are then implanted into the wafer 11 mounted on the support. At
this time, the driving shaft 13 is raised and lowered by the
elevation driving means 14, while the support plate 12 is tilted
horizontally or vertically by about 7 degrees, to execute a
scanning process in the Y-direction.
Moreover, at this time, the topmost and bottommost parts of the
wafer 11 are offset horizontally from each other by a distance X
due to the slope of the support plate 12. That is, there is a
difference in the distance that the ion beam A propagates from the
parallel ion beam radiating means 10 before reaching the topmost
and bottommost parts of the wafer 11. This difference brings about
a variation in the amount of ions distributed over and hence,
implanted into the wafer 11. These variations in the amount of ions
implanted into the wafer 11 create a variety of problems, such as
inconsistencies in the quality of the semiconductor devices
produced from the wafer. Some of the devices are even of
insufficient quality.
SUMMARY OF THE INVENTION
Therefore, one object of the present invention is to solve the
aforementioned problems by providing an ion implantation apparatus
that minimizes the difference in distance that an ion beam must
travel before reaching topmost and bottommost parts of a wafer
during the scanning of the wafer, whereby the ion-implantation
process is carried out uniformly across the surface of the
wafer.
Another object of the present invention is to provide an ion
implantation apparatus which can achieve such a uniform
distribution of ions for wafers of various sizes and produce
different characteristics in the wafers as the result of the
ion-implantation process.
In order to achieve the aforementioned objects, the present
invention provides a wafer scanning support which includes a scan
shaft pivotally mounted about a horizontal axis so that it can be
inclined relative to the vertical, an elevating member slidingly
coupled to said scan shaft so as to be movable therealong, a
driving motor for moving the elevating member up and down along the
scan shaft, and a wafer holder connected to the elevating member so
as to be movable therewith.
The wafer scanning support unit may also include horizontal
maintaining means for positioning the wafer holder in the
horizontal direction. The horizontal maintaining means includes a
horizontal transfer member coupled to the elevating member so as to
move therewith. On the other hand, a vertical maintaining means is
provided for positioning the wafer holder in the vertical
direction. The vertical maintaining means includes a vertical
transfer member coupled with an end of the horizontal transfer
member so as to move therewith.
The wafer holder can be incorporated into a tilter mounted to an
end of the vertical transfer member. The tilter is operative to
place the wafer holder in an upwardly facing position to facilitate
the loading or unloading of the wafer.
According to the present invention, the scan shaft can be inclined
at a predetermined position. As the elevating member is moved
upwardly and downwardly along the scan shaft during scanning, the
inclined wafer holder is moved along an inclined path corresponding
to the inclination of the scan shaft, whereby the ion beam travels
substantially the same distance to impinge all portions of the
wafer including the uppermost and bottommost parts. In addition,
the position of the scan shaft can be set based on the parameters
of the process, such as the size of the wafer and the desired
characteristics to be provided by the ion-implantation process.
Moreover, the horizontal and vertical maintaining means allow the
wafer support to be moved to the same loading and unloading
position irrespective of the position of the scan shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become clearer by referring to the following
detailed description of the preferred embodiment thereof made with
reference to the accompanying drawings, of which:
FIG. 1 is a schematic diagram of a conventional ion implantation
apparatus;
FIG. 2 is a schematic diagram of a wafer scanning support unit of
an ion implantation apparatus according to the present
invention
FIG. 3 is a perspective view of part of a wafer scanning support of
the ion implantation apparatus of the present invention;
FIG. 4 is a cross-sectional view of horizontal maintaining means of
the wafer scanning support;
FIG. 5 is a cross-sectional view of vertical maintaining means of
the wafer scanning support;
FIG. 6 is a sectional view of the coupling of the horizontal and
vertical maintaining means, of the present invention;
FIG. 7 is another schematic diagram of the wafer scanning support
unit of the ion implantation apparatus of the present invention, in
a loading or unloading state; and
FIG. 8 is a similar diagram of the wafer scanning support unit of
the present invention, but in an operational state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 2, the ion implantation apparatus of the
present invention includes a vacuum chamber 20 having an opening 22
at one side thereof for admitting an ion beam 21 propagating from
ion radiating means (not shown). A fixing member 30 is secured at
the bottom of the vacuum chamber 20, and a scan shaft 40 is
pivotally mounted to the fixing member 30 about a first horiontal
axis.
A first driving motor 41 is mounted to the top of the scan shaft
40. An elevating member 42 is slidingly fitted to the scan shaft 40
and is engaged with the first driving motor 41 so that it can be
reciprocated therealong by the first driving motor 41.
Furthermore, a scan shaft maintaining means 50 is engaged with the
lower part of the scan shaft 40 for pivoting the scan shaft 40 to a
given angular position. As shown in FIG. 3, the scan shaft
maintaining means 50 comprises a hinge pin 51 by which the scan
shaft 40 is pivotally mounted to a lateral surface of the fixing
member 30, an arcuate gear part 52 integral with the bottom part of
the scan shaft 40, and a driving gear 54 meshing with the teeth of
the arcuate gear part 52. A second driving motor 53 is coupled to
the driving gear 54, whereby the inclination of the scan shaft 40
can be set by rotating the driving gear 54 with the second driving
motor 53.
A horizontal maintaining means 60 is attached to the elevating
member 42. As shown in FIG. 4, the horizontal maintaining means 60
comprises a cylinder 61 mounted to the elevating member 42, a third
driving motor 63 having a threaded output shaft 62 and mounted to
one end of the cylinder 61, and a horizontal transfer member 64
extending into the other end of the cylinder 61 and threadingly
engaged with the screw shaft 62. In addition, a through-hole 65 is
formed at an end of the horizontal transfer member 64. The
horizontal transfer member 64 is moved forward or backward by the
screw shaft 62 when the screw shaft 62 is rotated by the third
driving motor 63.
On the other hand, a vertical maintaining means 70 is coupled to
one end of the horizontal maintaining means 60. The vertical
maintaining means 70 is structurally similar to the horizontal
maintaining means 60. As shown in FIG. 5, the vertical maintaining
means 70 comprises a cylinder 71, a fourth driving motor 73 mounted
to one end of the cylinder 71, and a vertical transfer member 74
extending into the cylinder 71 from the other side thereof side
thereof and mated with a threaded output shaft 72 of the fourth
driving motor 73.
The vertical maintaining means 70 is coupled to one side of the
horizontal maintaining means 60 by a rotary coupling 80, so as to
be rotatable about a second horizontal axis parallel to that about
which the scan shaft 40 can pivot. As shown in FIG. 6, the rotary
coupling 80 includes a protrusion 81 defining a hole 81a
therethrough. One end of the protrusion 81 is fixed to one side
surface of the cylinder 71, and the other end of the protrusion 81
is fixed to the end of cylinder 61. A fifth driving motor 83 is
also fixed to the end of the cylinder 61. A rotary output shaft 82
of the fifth driving motor 83 extends through through-hole 65 and
into the hole 81a in the protrusion 81, where it is fixed to the
protrusion 81. A cap member 84 is formed at the side of the
cylinder 71 for supporting the protrusion 81.
Because the end of the rotational shaft 82 is fixed to the
protrusion 81, the rotation of the output shaft 82 of the fifth
driving motor 83 can pivot the vertical maintaining means 70 to a
predetermined angular position.
In addition, a tilter 90 is coupled to an upper end of the vertical
maintaining means 70 for facilitating the loading or unloading of a
wafer W. The tilter 90 includes a supporting member 91 mounted to
an end of the vertical transfer member 74, a rotary member 92
coupled with the supporting member 91, and a holder 93 coupled to
an end of the rotary member 92 for supporting the wafer W. The
rotary member 92 can be rotated by driving means, e.g. a motor (not
shown), about a plane inclined by about 45.degree. relative to the
vertical, whereby rotation of the rotary member 92 relative to the
supporting member 91 can move the wafer holder 93 between
respective positions at which the wafer holder 93 faces the opening
22 in the vacuum chamber 20 and faces upwardly to facilitate the
loading and unloading of a wafer.
The remainder of the ion implantation apparatus is conventional and
can take the form of that shown in FIG. 1. In the ion implantation
apparatus of the present invention having a wafer support as
described above, the wafer W is supported by the tilter 90 while a
vacuum of a predetermined level is maintained in the vacuum chamber
20.
At this time, the inclination of the scan shaft 40 in the vertical
direction is set depending on certain parameters, namely the size
of the wafer W or characteristics desired of the ion implantation.
If a change is made to such parameters, a value indicative of the
change is input to a controller (not shown) and the controller then
drives the second driving motor 53 accordingly to change the
inclination of the scan shaft 40.
When the inclination of the scan shaft 40 is changed, the position
of the vertical maintaining means 70 and tilter 90 relative to the
scan shaft 40 is changed by the driving motor 83 of the connecting
means 80. Specifically, the fifth driving motor 83 drives the
rotational shaft 82 over an angle necessary to keep the vertical
maintaining means 70 in its vertical state, i.e., to maintain its
inclination relative to the scan shaft 40.
After the scan shaft 40 is positioned, the wafer W is loaded onto
the tilter 90. In this situation, the rotary member 92 is rotated
180 degrees so that the holder 93 is positioned to face upwards, as
shown in FIG. 7. The horizontal and vertical maintaining means 60,
70 allow the loading/unloading position to remain fixed in the
apparatus irrespective of the inclined position of the scan shaft
40.
Next, the horizontal position of the tilter 90 is set by the
horizontal maintenance means 60. That is, the third driving motor
63 operates to rotate the screw shaft 62, thereby moving the
horizontal transfer member 64. Hence, the tilter 90, is positioned
in the horizontal direction. On the other hand, the vertical
transfer member 74 is moved vertically by the screw shaft 72 as
rotated by the fourth driving motor 73. Accordingly, the tilter 90
mounted to the vertical transfer member 74 is positioned in the
vertical direction.
The tilter 90 is moved in this way to place the holder 93 at the
loading (or unloading position). A robot or other similar means
(not shown) operates to load the wafer W onto the holder 93 (or to
unload the wafer W therefrom).
After the wafer W has been loaded onto the holder 93, the rotary
member 92 is driven to rotate the holder 93 to its initial state,
and the horizontal and vertical maintaining means 60, 70 operate to
position the wafer W close to the opening 22.
At this time, the ion beam 21 produced by the ion radiating means
(not shown) is induced through the opening 22 into the vacuum
chamber 20, and the first driving motor 41 repeatedly rotates its
output shaft forward and backward to raise and lower the wafer W so
that the wafer is scanned with the ion beam. In this case, the
elevating member 42 is raised and lowered along the inclined scan
shaft 40. The horizontal maintaining means 60 coupled to the
elevating member 42, and the vertical maintaining means 70, and the
tilter 90, are raised and lowered with the elevation member 42 so
that ions are distributed over the surface of the wafer W mounted
at the holder 93 of the tilter 90. Because the scan shaft is set at
a predetermined inclination, the ion beam will travel substantially
the same distance when it impinges the wafer W irrespective of the
movement of the wafer W in the vertical direction.
After the ion implantation process is completed, the horizontal and
vertical maintaining means 60, 70, and tilter 90 operate to place
the holder 93 at the unloading position. Then, the ion-implanted
wafer W is unloaded, and a new wafer W is loaded. Next, the
aforementioned processes are sequentially performed to execute the
ion implantation processes on the new wafer W.
As described above, the present invention makes it is possible to
set the scan shaft to an inclination, relative to the vertical,
based on the parameters of the ion implantation process, such as
wafer size, and to maintain the slope of the scan shaft during the
scanning of the wafer with the ion beam, and thereby minimize the
difference in the distance that the ion beam travels to the topmost
and bottommost parts of the wafer. Accordingly, the present
invention makes it possible to distribute the ions uniformly over
the surface of the wafer and thus enhance the quality of the wafer
product from which the semiconductor devices will be produced.
Although the present invention has been described above with
respect to the preferred embodiment thereof, various changes
thereto and modifications thereof will be apparent to those of
ordinary skill in the art. All such changes and modifications are
seen to be within the true spirit and scope of the invention as
defined by the appended claims.
* * * * *